The synovial fluid adiponectin-leptin ratio predicts pain with knee osteoarthritis.

The relationship between adipokines, such as leptin and adiponectin, and cartilage degeneration is being increasingly recognized. We asked what the relationship is between these hormones and patient-reported knee osteoarthritis (OA) pain. We collected demographic data, Short Form McGill Pain scores, Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain scores, and synovial fluid (SF) samples from 60 consecutive patients with severe knee OA at the time of joint replacement surgery. SF samples were analyzed for leptin and adiponectin using specific ELISA. Non-parametric correlations and linear regression modeling were used to identify the relationship between the adipokines and pain levels. The correlations between the individual adipokines and the pain scales were low to moderate and consistently less than that for the corresponding adiponectin/leptin (A/L) ratio. Linear regression modeling showed that the A/L ratio was a significant predictor of a greater level of pain on the MPQ-SF (p=0.03) but not the WOMAC pain scale (p=0.77). A greater A/L ratio was associated with less pain with severe knee OA and this metabolic pathway may represent a target for novel therapeutics.